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In modern electric traction drives, on-line monitoring offers the advantage to decrease maintenance cost and increase the reliability. Especially, the electrical insulation is one of the most vulnerable components of an ac machine. Fast switching of the inverter results in high output voltage slew rates increasing the stress on the insulation as well as the rate of deterioration. The described stator...
At inverter-fed traction drives stray currents due to parasitic capacitances in frequency converters and machine cause high frequency voltage components spreading into all conductive components of the drive system. These hf voltages are harmful and origin from the inverter side through fast switching power semiconductors with high levels of output voltage steepness. Additionally overvoltage at the...
Reflected wave transient phenomena in voltages and currents of inverter-fed drives caused by voltage source inverters (VSI) operating with pulse width modulation (PWM) with high dv/dt rates are well known and analyzed in many studies. The reflection phenomena occurring at the machine terminals, resulting in high overvoltages are one reason for the stress and aging mechanism of AC machines insulation...
Stator insulation defects in the machine winding of traction drives can be analyzed by evaluating the current response resulting to inverter induced voltage injection. Due to effects occurring during the aging of the insulation, e.g. change of parasitic electrical components, deviations of the high frequency components of the current response can be monitored. The insulation degradation of a stator...
In order to investigate insulation degradation of high voltage traction drives, series of measurements on form wound coil specimens have been done. These stator bars have been aged by different accelerated aging cycles until the failure of the insulation is determined by voltage exposure tests. After every aging cycle the dissipation factor (tan δ) and capacitance (C) of the insulation system is recorded...
The proposed online monitoring method detects insulation defects in a machine by evaluating the current response after a certain voltage step excitation is applied. The transient current response is analyzed to determine the status of an electrical machine insulation regarding aging, in a longer perspective. If insulation degradation occurs the parasitic winding components (e.g. winding capacitances)...
Stator insulation defects in traction drives machine windings can be analyzed by evaluating the current response after a voltage step excitation. The status of the stator insulation material regarding aging, is observed in a longer perspective. Because of the fact that insulation degradation of a stator winding system is a long developing process, a deviation of the parasitic electrical components...
A new optimization approach for internal forced air-cooled traction drives is presented integrating multi-physic performance evaluations. Here, the coupling of aero- and thermodynamic cooling performance with electromagnetic performance analysis is applied. For determining electromagnetic properties FEA (finite element analysis) is use. The aero-/ thermodynamic performance is evaluated with analytical...
This paper applies a multi-physics optimization exemplary considering electromagnetic and aero-/ thermo-dynamic performance. Today, electrical drives used for railway traction face limited space constrains which leads to high power density machines. That requires advanced cooling concepts that are able to highly effectively discharge heat without adding more volume and weight in the boggy. A novel...
In modern drive applications fed by voltage source inverters, monitoring systems are of advantage to reduce the maintenance costs and prevent outages. The proposed insulation monitoring method detects stator insulation defects by evaluating the current's transient response after step excitation by the inverter. Due to fast switching of the voltage source inverter at high output voltage dv/dt rates,...
In this work a method to detect insulation degradation of an adjustable speed drive (ASD) based on analyses of the transient current reaction caused by inverter switching is proposed. The drive system consists of an inverter fed three phase induction machine with 1.4MW. The standard current sensors are used to analyze the transient signal ringing to extract an insulation state indicator of the winding...
In the electrical machines, operated in railway traction drives, the growth of power density requires overproportional more heat to be discharged which leads to the need for more and more advanced cooling techniques. A novel optimization and evaluation approach for internal air cooled traction machines will be presented in this paper. It analyses and investigates the thermo-aero- and thermodynamic...
The growth of power density in traction motors requires disproportionally more heat to be discharged which leads to the need for more and more advanced cooling techniques. In this paper a novel evaluation and optimization approach for internal air cooled traction machines will be presented. It investigates the electromagnetic performance combined with the aero- and thermodynamic cooling performance...
The demand of monitoring systems to prevent a breakdown of electrical machines is continuously increasing. Regarding economic issues, usage of system resources and additional components to establish monitoring is restricted. With the method proposed, the evaluation of the stator insulation condition of all three phases is possible using only the two current sensors already available in modern drive...
In modern traction drives the application of monitoring systems is growing to ensure continuous operability. Because of the voltage source inverters (VSI) and the high steep voltage change (dv/dt), increased stress of the winding insulation exist. Stator insulation faults are common reasons for a machine breakdown. Insulation health state can be examined by evaluating the transient reaction to a voltage...
Application of monitoring systems is growing in modern drive applications to ensure continuous operability. Insulation health state can be examined offline by evaluating the transient reaction to a voltage step excitation. Using the inverter as a source of excitation, it is possible to perform an insulation test by evaluating the resulting transient current sensor signals available in modern drives...
A novel life-cycle monitoring and voltage-managing device for dc-link electrolytic capacitors in pulsewidth modulation converters is presented. The system performs online identification of the capacitor's equivalent series resistance (ESR) in order to detect the life-cycle status and permit preventive maintenance. The ESR detection is based on the capacitor's ac losses calculated from voltage/current...
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